Several known solutions exist for sharpening chain saw teeth, all of them being limited either to the use in the service and maintenance facilities, or to different embodiments of hand files. For instance, a solution is disclosed in the U.S. Pat. No. 3,172,306 enabling guidance of the file in the set direction providing an accurate geometry of cutting surfaces of each tooth. The drawback of the said solution is the slowness of the sharpening and the inability of ensuring the repeatability of sharpening even with the very next tooth. The device is unstable when used and unsuitable for use in an arbitrary location. Another solution is known from the U.S. Pat. No. 4,762,027 where a grinding wheel travels during sharpening over an arch determined by a bearing located transversally to the chain plane. Such an arrangement results in the convexity of the cutting edge of a tooth representing a situation which is the opposite to what is wanted. Still another solution disclosed in, the U.S. Pat. No. 4,319,502 comprises a grinding wheel swinging in a vertical plane, however, this solution did not remedy the problem of the convexity of the surface to be sharpened. In addition, the said device is too big and too heavy for field work, and is also unfavourable with regard to the power consumption.